Photoshop CS3 Lag in Vista

I have a problem, which is apparently quite popular, with Adobe Photoshop CS3. Everything takes a long time to respond; button rollovers, menus, etc. The lag is so bad that it is hard to complete projects using the software. I found many fixes to the problem, none of which worked for me.

I tried:

Different things with the default printer (I do not have a network printer)
Compatibility mode
Disabling visual effects

My computer never has any lag issues with any other software, and the lag occurs when a project is not even open. My processor is running at ~3% with no other applications open. Photoshop uses about 125MB out of 2GB of RAM.